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Hip and groin pain is one the most frequent complaints in male soccer, affecting up to 70% of players during a soccer season.1 ,2 The incidence and severity of hip and groin injuries have primarily been described in the past using time-loss definitions, as suggested by consensus statements concerning soccer-injury registration.3 However, as many soccer-related hip and groin injuries present as painful overuse conditions with an insidious onset, and fluctuating long-standing symptoms, defining the presence of these injuries using time-loss definitions provides a very limited insight into the true extent of hip and groin problems.1–6
In 2011, we published the Copenhagen Hip and Groin Outcome Score (HAGOS), a self-reported questionnaire evaluating hip and groin disability status from 0 to 100, where 100 indicates no hip and groin problems, and 0 indicates severe hip and groin problems.7 This questionnaire was developed to include items relevant not only for physically active individuals in general, but also for athletes such as soccer players. HAGOS showed promise as a reliable, valid and responsive measure of hip and groin disability outcome and injury status, revealing that patients with long-standing hip and groin pain had a low HAGOS (<50 points) in those subscales that were related to participation in physical activity, sport and quality of life.7 A substantial proportion of participants in this study were male soccer players with hip and groin pain, indicating that HAGOS may be a highly relevant measure for this group of athletes.7 However, as HAGOS has never been assessed exclusively in this group of athletes, its performance in this population (healthy soccer players) is unknown.
Therefore, the reference values of HAGOS based on injury-free soccer players need to be established, to enable future interpretation of HAGOS in male soccer players with hip and groin pain. The aim of this study was to establish reference values for HAGOS in hip and groin injury-free male soccer players.
This study is based on data from a large cohort study investigating hip and/or groin pain, self-reported outcome, clinical characteristics, muscle strength, range of motion and radiological findings in male soccer players. All participants provided written informed consent according to the Helsinki Declaration. The project was approved by the Danish National Committee on Health Research Ethics (H-2-2010-127).
Forty teams including 725 players were invited to join the study. Twenty-five participants failed to meet the inclusion criteria of being at least 18 years of age (n=10), or failed to answer the questionnaire correctly (n=15). Thus, a total of 700 players, representing 40 teams (divisions 1–4) in Eastern Denmark, were eligible for the study. The soccer players were all playing at a subelite level. Four hundred and forty-four of the 700 players were hip and groin injury-free at the time of initiation of the study and therefore included. These players were 23.6 (4.4) years of age, and were training in soccer 3.4 (1) times/week.
All players answered HAGOS7 within the first 6 weeks of resuming the new season (July/August 2011). Data collection was performed by observers from the Arthroscopic Centre Amager. Data-collection sessions were performed with each team before or after a training session. The players were asked to answer two self-reported questionnaires: (1) HAGOS7 and (2) a self-reported questionnaire concerning descriptive data and injury status. HAGOS is a questionnaire evaluating hip and/or groin disability7 and consists of six subscales (Symptom, Pain, Activities of Daily Living, Sports and Recreation, Participation in Physical Activities and Quality of Life). Each subscale is scored as a percentage of the total possible score, ranging from 0 to100, where 0 indicates severe problems and 100 indicates no problems. HAGOS has proven to be valid, reliable and responsive for evaluating individuals with hip and/or groin pain, with the original study including a large proportion of male soccer players.7
The questionnaire including self-reported descriptive data and injury status covered general information (age, height, weight, number of soccer training sessions per week and level of play) and a self-reported history of hip and/or groin pain in the current and previous seasons.
Descriptive variables were presented as mean±1 SD. As the dependent variables (HAGOS) did not show a normal distribution, non-parametric statistics were used for all analyses. The influence of age and playing level on HAGOS was analysed by Spearman correlation. Median and IQRs were presented for all results. An independent measures test (Mann-Whitney) was used for comparison between groups. Reference intervals (95%) for scores of each subscale from hip and groin injury-free players are given,8 constituted by the 5th–100th centile.
HAGOS were obtained for all 444 included participants. One subscale score could not be calculated for six different players due to missing items. An initial analysis showed that of the 444 soccer players who were hip and groin injury-free at the beginning of the season, 143 had experienced hip and/or groin pain in the previous season. The initial analysis also showed that the players who had experienced hip and/or groin pain in the previous season displayed lower scores than asymptomatic players for all HAGOS subscales (p<0.001; table 1). Therefore, only values from the 301 soccer players who had no hip and groin pain at the time of testing (in the beginning of the new season), and no hip and groin pain in the previous season, were used for calculating reference values for hip and groin injury-free soccer players. Age and playing level were not correlated (Spearman r<0.1) to HAGOS subscales in hip and groin injury-free soccer players (p>0.05).
The 5th–100th centiles, constituting the 95% reference range for the hip and groin injury-free soccer players HAGOS subscale scores, are: pain 80.1–100; symptoms: 64.3–100; activities of daily living: 80.3–100; sport and recreational activities: 71.9–100; participation in physical activity: 75–100 and quality of living: 75–100 (figure 1).
The purpose of the present study was to establish reference data for HAGOS in hip and groin injury-free male soccer players, in order to provide a basis for future interpretation of HAGOS in male soccer players with hip and groin pain. The present study showed that the players who had experienced hip and/or groin pain in the previous season displayed lower scores than the rest of the players who did not, for all HAGOS subscales (p<0.001). These players experienced more symptoms, decreased function and decreased quality of life than the rest of the players, and therefore only soccer players who had no hip and groin pain in the beginning of the new season, and no hip and groin pain in the previous season, were considered appropriate as hip and groin injury-free references.
Scores from self-reported questionnaires, such as the Knee injury and Osteoarthritis Score (KOOS), have previously been shown to be related to previous injury status in male and female soccer players, with higher scores (close to 100 points) in injury-free soccer players.9 ,10 As in the present study, a previous study including KOOS suggests that the Symptoms subscale seems to provide the lowest subscale score of the different subscales, indicating that symptoms are being experienced in injury-free individuals. This may, however, be explained by the fact that some of the questions in the Symptoms subscale of both HAGOS and KOOS are not necessarily directly related to injury, such as questions related to joint clicking and joint stiffness. These symptoms reported by hip and groin injury-free players may, especially when experienced in milder forms, be related to sports activity in itself and thus be reflected in a lower HAGOS Symptoms subscale, compared with the other HAGOS subscales.
Interestingly, a previous study has shown that KOOS is able to predict knee injuries when the total score is below 80 points.10 Whether total scores should be introduced in injury prediction is questionable as composite scoring should be avoided.11 However, the lower HAGOS reference limits provide cut-points for abnormal scores of the different HAGOS subscales, and these lower limits may therefore be helpful in identifying players at risk of future hip and groin injury. However, the predictive validity of HAGOS subscales remains to be investigated in future studies.
Lower HAGOS subscales are seen in soccer players who have experienced hip and/or groin pain in the previous season, compared with those who have not. Median HAGOS subscale scores in hip and groin injury-free soccer players are in proximity to the maximum score (100 points), and scores of 64–80 provide the lower limit for the six subscale 95% reference range in soccer players.
The authors would like to thank the participating clubs and Martin Nielsen, Michael Madsen, Mads Langelund and Lasse Lundquist for assisting with the data collection.
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